Infiniti G37 Coupe. Manual - part 502

P0122, P0123, P0227, P0228 TP SENSOR

EC-189

< COMPONENT DIAGNOSIS >

[VQ37VHR]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> GO TO 6.

6.

REPLACE ELECTRIC THROTTLE CONTROL ACTUATOR

1.

Replace malfunctioning electric throttle control actuator.

2.

Go to 

EC-189, "Special Repair Requirement"

.

>> INSPECTION END

7.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-38, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000001734019

1.

CHECK THROTTLE POSITION SENSOR

1.

Turn ignition switch OFF.

2.

Reconnect all harness connectors disconnected.

3.

Perform 

EC-18, "THROTTLE VALVE CLOSED POSITION LEARNING : Special Repair Requirement"

.

4.

Turn ignition switch ON.

5.

Set selector lever to D (A/T) or 1st (M/T) position. 

6.

Check the voltage between ECM harness connector and ground.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 2.

2.

REPLACE ELECTRIC THROTTLE CONTROL ACTUATOR

1.

Replace malfunctioning electric throttle control actuator.

2.

Go to 

EC-189, "Special Repair Requirement"

.

>> INSPECTION END

Special Repair Requirement

INFOID:0000000001734020

1.

PERFORM THROTTLE VALVE CLOSED POSITION LEARNING

Refer to 

EC-18, "THROTTLE VALVE CLOSED POSITION LEARNING : Special Repair Requirement"

>> GO TO 2.

2.

PERFORM IDLE AIR VOLUME LEARNING

Refer to 

EC-19, "IDLE AIR VOLUME LEARNING : Special Repair Requirement"

>> END

ECM

Ground

Condition

Voltage

Connector

Terminal

F101

30 [TP sensor 1 (bank 1)]
31 [TP sensor 1 (bank 2)]

Ground

Accelerator pedal

Fully released

More than 0.36V

Fully depressed

Less than 4.75V

34 [TP sensor 2 (bank 1)]
35 [TP sensor 2 (bank 2)]

Fully released

Less than 4.75V

Fully depressed

More than 0.36V

EC-190

< COMPONENT DIAGNOSIS >

[VQ37VHR]

P0125 ECT SENSOR

P0125 ECT SENSOR

Description

INFOID:0000000001910832

The engine coolant temperature sensor is used to detect the engine
coolant temperature. The sensor modifies a voltage signal from the
ECM. The modified signal returns to the ECM as the engine coolant
temperature input. The sensor uses a thermistor which is sensitive to
the change in temperature. The electrical resistance of the ther-
mistor decreases as temperature increases.

<Reference data>

*: These data are reference values and are measured between ECM terminal 71
(Engine coolant temperature sensor) and ground.

CAUTION:

Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in damage to the ECM’s transis-
tor. Use a ground other than ECM terminals, such as the ground.

DTC Logic

INFOID:0000000001734022

DTC DETECTION LOGIC

NOTE:
If DTC P0125 is displayed with P0117 or P0118, first perform the trouble diagnosis for DTC P0117 or
P0118. Refer to 

EC-184, "DTC Logic"

.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next test.
1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

>> GO TO 2.

2.

CHECK ENGINE COOLANT TEMPERATURE SENSOR FUNCTION

With CONSULT-III

SEF594K

Engine coolant temperature

°

C (

°

F)

Voltage*

V

Resistance

k

Ω

–10 (14)

4.4

7.0 - 11.4

20 (68)

3.5

2.37 - 2.63

50 (122)

2.2

0.68 - 1.00

90 (194)

0.9

0.236 - 0.260

SEF012P

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0125

Insufficient engine cool-
ant temperature for 
closed loop fuel control

• Voltage sent to ECM from the sensor is not 

practical, even when some time has passed 
after starting the engine.

• Engine coolant temperature is insufficient for 

closed loop fuel control.

• Harness or connectors

(High resistance in the circuit)

• Engine coolant temperature sensor
• Thermostat

P0125 ECT SENSOR

EC-191

< COMPONENT DIAGNOSIS >

[VQ37VHR]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

1.

Turn ignition switch ON.

2.

Select “DATA MONITOR” mode with CONSULT-III.

3.

Check that “COOLAN TEMP/S” is above 10

°

C (50

°

F).

With GST

Follow the procedure “With CONSULT-III” above.

Is it above 10

°

C (50

°

F)?

YES

>> INSPECTION END

NO

>> GO TO 3.

3.

PERFORM DTC CONFIRMATION PROCEDURE

With CONSULT-III

1.

Start engine and run it for 65 minutes at idle speed.
If “COOLAN TEMP/S” increases to more than 10

°

C (50

°

F) within 65 minutes, stop engine because

the test result will be OK.

CAUTION:

Be careful not to overheat engine.

2.

Check 1st trip DTC.

With GST

Follow the procedure “With CONSULT-III” above.
Is 1st trip DTC detected?

YES

>>

EC-191, "Diagnosis Procedure"

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000001734023

1.

CHECK GROUND CONNECTION

1.

Turn ignition switch OFF.

2.

Check ground connection M95. Refer to Ground Inspection in 

GI-41, "Circuit Inspection"

.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> Repair or replace ground connection.

2.

CHECK ENGINE COOLANT TEMPERATURE SENSOR

Refer to 

EC-191, "Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Replace engine coolant temperature sensor.

3.

CHECK THERMOSTAT OPERATION

When the engine is cold [lower than 70

°

C (158

°

F)] condition, grasp lower radiator hose and confirm the engine

coolant does not flow.
Is the inspection result normal?

YES

>> GO TO 4.

NO

>> Repair or replace thermostat. Refer to 

CO-22, "Removal and Installation"

.

4.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-38, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000001910833

1.

CHECK ENGINE COOLANT TEMPERATURE SENSOR

1.

Turn ignition switch OFF.

2.

Disconnect engine coolant temperature sensor harness connector.

3.

Remove engine coolant temperature sensor.

EC-192

< COMPONENT DIAGNOSIS >

[VQ37VHR]

P0125 ECT SENSOR

4.

Check resistance between engine coolant temperature sensor
terminals by heating with hot water as shown in the figure.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace engine coolant temperature sensor.

Terminals

Condition

Resistance

1 and 2

Temperature 

°

C (

°

F)

20 (68)

2.37 - 2.63 k

Ω

50 (122)

0.68 - 1.00 k

Ω

90 (194)

0.236 - 0.260 k

Ω

JMBIA0080ZZ